On my Hiedleburg (Blaupaunkt?) Radio on my 88 Westy the code is set at
the factory to 1000. That should still be the code unless you or the PO
(if you bought the Quantum used) changed it. As someone else mentioned
ina previous message, the fist digit can only be a 1.  I would try 1000
as many owners never changed their original code.  If you have the
original booklet that comes with the radio, it has a card attached where
the owner is supposed to write the code down.

Hope this helps

Tim Fast
88 Westy ("The Battle Bus")
West Des Moines, IA